The invention relates generally to electrocardiogram (ECG) monitoring systems and, more particularly, to determining and indicating the quality of ECG signals.
ECG monitoring systems may be designed to generate alarms indicative of patient medical conditions as well as equipment failure and/or inability to function properly. The ECG monitoring systems may generate “false alarms”, which do not result from a medical problem of the patient, but are often based on errors in internal signal processing or from detached or failed leads. False crisis alarms, in particular, waste valuable nursing and emergency staff resources because they may result in an unnecessary rapid response that may divert resources from other patients. Many ECG systems are capable of reliably detecting failed or detached leads, often notifying an operator of the detached or failed leads via an alarm. In addition, many ECG systems provide an indication of a temporary inability to process one or more ECG waveforms. Such an indication is commonly known as an artifact alarm.
Although equipment lead and artifact alarms may have a low priority and often cease when an artifact ends, they can generate display clutter and do not, in general, provide actionable information. Nonetheless, the alarm should still be investigated by monitoring personnel. Additionally, a signal problem often occurs on a channel other than the primary viewing channel, and the default screen shown on a monitor often does not contain information that allows for the identification of which channel the alarm is associated with. Accordingly, an operator often must search for the proper screen to assess the artifact. By the time the proper screen is found, often the problem that initiated the false alarm event has already passed. Accordingly, such false alarms serve as a distraction to medical personnel.
In order to minimize the distracting impact of false alarms, several techniques have been implemented. One technique includes reducing the annoyance due to lower-severity alarms, such as an alarm that results from a failed lead. That is, displays and acoustic stimuli associated with lower-severity alarms are designed in such a manner as to minimize their level of annoyance on the operator and patient by having, for instance, a proportionately lower acoustic noise level or a proportionately less distracting visual indicator. The caregiver may become unaware that there is a signal quality problem because of a “cry wolf” effect. That is, due to a series of equipment or signal related alarms, the operator may fail to investigate other alarms because of an assumption that the alarms are also related to the signal quality or equipment. A consequence of ignoring alarms is that the monitoring may become ineffective or have reduced sensitivity to serious conditions.
Another approach by which the ECG monitoring false alarm problem has been addressed is to notify medical professionals of alarms only when necessary. To implement this approach, monitoring locations have been developed where specialized personnel are responsible for the monitoring of ECG signals. That is, rather than having monitors located at bedside or at a nursing station, remote monitoring locations monitor ECG signals from multiple patients, and alarms generated by many patients are pre-screened by a human observer, sometimes called a tele-technician. When an alarm is raised, the tele-technician assesses the proper screen and decides whether to notify medical personnel such as nurses, physicians, and emergency response teams. Such an environment, however, may result in distractions that arise from multi-tasking. For example, a tele-technician may be adjusting a display to see a first patient's record in more detail, while at the same time a more critical alarm is registered by another patient. In such a situation, the critical alarm may cause the tele-technician to forget about the task of looking at the first patient's record in more detail. As such, despite the fact that a tele-technician's only responsibility may be to monitor signals, the tele-technician may still readily become overwhelmed by alarms when more than a few patients happen to have simultaneous critical alarms. Furthermore, though the alarm may sound a critical signal, it may be a false alarm, further exasperating the situation.
Communication problems can also arise due to the monitoring being done at a remote location. For example, a tele-technician may not be in close communication with a hospital ward, thus the tele-technician may have difficulty contacting hospital staff. Accordingly, due to communication issues and distraction, legitimate alarms may be missed even where alarms are monitored by dedicated tele-technicians.
Accordingly, it would be desirable to design a system capable of displaying signal quality independently of displaying waveform data, and of using the signal quality value to minimize false alarms in an ECG monitoring system.